I have not played the Big Bertha. It came out after the SLDR.
I have played the SLDR for several months now. It is a very good driver with nice meter speed.
It is a very straight driver. Ball does not curve very much even when you miss the ding or in heavy winds.
It is a lower boring driver and my only complaint is that you have to watch driving over tree on a few holes like Congressional.
Can not go wrong with this driver and will keep until the R-1, Bertha 96 or Covert 100.
My current driving average is 288 with this driver. That include many times when I hit less than Driver on a few holes.